Electric incandescent lamp



July 16, 1935. o. RECHER 2,008,594

ELECTRIC INCANDESCENT LAMP Filed Dec. 16, 1952 m n or." 0170 lPec/zer Patented July 16, 1935 UNITED STATES PATENT OFFICE Application December 16, 1932, Serial No. 647,664 In Germany January 12, 1932 2 Claims.

Electric incandescent lamps having an insulated cap with contacts thereon are known. One of these contacts is commonly in the form of a screw threaded part in order to screw into the usual Edison screw holder.

The object of the invention is to eliminate this screw thread on the insulated cap while still employing the usual screw holder, and itemploys, in known manner, projections for guiding and holding the cap in the holder. According to the invention these projections are provided on the sleeveless insulated socket which is most simply made of glass integral with the lamp bulb, and are located on a helix corresponding with the thread in the socket, one of them, preferably lengthened, also being formed as a contact, while the other contact is as usual provided in the end of the cap. The projections of the invention are not to be confused with the pins used in the bayonet type of cap and holder, still less so since here one of the projections makes the electrical connection with the socket thread.

The accompanying drawing illustrates an embodiment of the invention.

Figure l is a side elevation of a lamp with the cap in section.

Figure 2 is a plan of Figure 1.

The cap a provided at the base of the lamp bulb is made integrally of glass, but whilst the bulb is of glass, the cap piece could also be made of another insulating material. The lamp bulb contains the usual filament. The cap a is not provided with the usual threaded metal sleeve, but is provided on its periphery with for example three unresilient wart-like projections b, c, d arranged on a helix, projecting from the cap material itself and guiding the cap when the lamp is screwed into the socket of the usual threaded holder. The projection d is elongated and at the same time forms a connecting contact to which the lead 1 of the filament sealed into the stem e is connected, while the other lead g of the filament is led to the connecting contact h in the end of the cap. To form the contact on the projection 5 d the latter is provided with a thin metal covering on its outer surface, which furnishes an adequate surface in contact with the thread of the holder.

The number of projections in the cap is not limited and may differ from the example.

What I claim is:-

1. An electric lamp for coaction with a threaded socket, comprising a one-piece envelope having a base portion of insulating material formed thereon, said base having formed integrally thereon separate projections of the same material, spaced from each other about the base in a spiral path having the same pitch as the socket, the base width of the projections being substantially the same as the pitch of the threads of the socket, and adapted to coact therewith, at least one of the projections being elongated.

2. An electric lamp for coaction with a threaded socket, comprising a one-piece glass envelope 5 having a base portion of glass formed thereon, a filament in said envelope lead for said filament, said base having separate glass projections formed integrally thereon thereon, spaced from each other about the base in a spiral path having the same pitch as the socket, the base width of the projections being substantially the same as the pitch of the threads of the socket, and adapted to coact therewith, one of the projections being elongated, and having one of said leads extending therethrough, for contact with the shell of the socket.

OTTO RECHER. 

